1. Field of the Invention
The present invention relates to an elastic wave device including an elastic wave element and a method for manufacturing the same, and more particularly, relates to an elastic wave device including an elastic wave element including a piezoelectric layer with a small thickness and a method for manufacturing the same.
2. Description of the Related Art
Various elastic wave devices including surface acoustic wave elements or boundary acoustic wave elements have been proposed. In an elastic wave device of this kind, in order to promote a reduction in profile, an elastic wave element is mounted on a mounting substrate by a flip chip bonding method.
In order to further promote a reduction in profile, Japanese Unexamined Patent Application Publication No. 11-251866 discloses a structure in which a surface acoustic wave element is sealed by an external resin layer. More specifically, in Japanese Unexamined Patent Application Publication No. 11-251866, the surface acoustic wave element is mounted on a mounting substrate by a flip chip bonding method. A buffer resin layer is disposed so as to cover the surface acoustic wave element, and an external resin layer is disposed on the outer side portion of the buffer resin layer. The buffer resin layer is provided in order to achieve stress relaxation and electrical insulation. The buffer resin layer is composed of a silicone resin or the like. On the other hand, the external resin is provided in order to achieve mechanical protection and enhancement in moisture resistance. The external resin layer is composed of an epoxy resin or the like.
In the elastic wave device described in Japanese Unexamined Patent Application Publication No. 11-251866, resin molding is performed using a silicone resin, an epoxy resin, or the like such that the resin is in contact with a piezoelectric substrate having poor thermal conductivity, and thus, the heat-dissipating property is unsatisfactory, which is a problem. The characteristics of the elastic wave element change with temperature. Consequently, unless the heat-dissipating property is satisfactory, stability in intended resonance characteristics and filter characteristics is impaired.